The present invention relates generally to data disk drives, and, more specifically, to shock protection thereof.
A direct access storage device (DASD) commonly referred to as a disk drive typically includes a plurality of data storage disks mounted on a common spindle which in turn is rotatably mounted to a housing. A motor rotates the spindle and disks and may be formed integrally inside the spindle itself. Data is written to and read from each of the disks by a corresponding read and write access head. The access head and disks may take any conventional form such as those commonly used for magnetically storing data in typical digitally programmable computers such as personal computers (PCs).
The access heads are in turn supported on respective suspension arms which are cantilevered from a common pivot shaft also rotatably mounted to the housing. The shaft, and in turn the suspension arms and access heads, may be pivoted or rotated in any conventional manner for positioning the access heads at any desired location over the several rotating data disks. This is typically accomplished using a conventional voice coil motor (VCM) which includes a pair of vertically spaced apart permanent magnets attached to the top and bottom of the housing and between which is positioned a coil fixedly joined to the pivot shaft opposite to the suspension arms.
In typical computer applications, such as PCs and laptop computers, available space for the disk drive is limited and therefore provides a critical limit in disk drive size and volume. Disk drives are constantly being improved to maximize the amount of data storage capability, typically expressed in gigabytes, in a minimum volume. This is accomplished in part by stacking closely together several data disks on the common spindle. In a high capacity disk drive of 3.5 inch form factor, about eight data disks may be mounted on a common spindle with a spacing between the disks of about 2.5 mm. In this extremely small space is positioned a respective suspension arm and corresponding access head for writing data to and reading data from the disks. Accordingly, during operation of the disk drive, the suspension arms are extremely close to the surface of the respective disks which are therefore subject to shock damage.
The centerline axis of the disk spindle defines a Z axis along which axis shock is a significant design parameter. In the event of an excessive Z-shock which may occur by bumping or dropping the disk drive, one or more of the access heads may physically contact the corresponding data disk causing damage to these components and the loss of data stored on the disk at the contact location. Undesirable contact between the access head and the disk may occur by the combined vibratory deflection of the suspension arm and the disk itself, with differential movement therebetween on the order of tenths of a millimeter being significant enough to effect interference contact unless suitable shock protection or isolation is provided.
Conventional shock isolators are typically in the form of elastomeric washers disposed between the housing at its mounting flanges and the chassis of the computer. However, in view of the critical space limitations within modern computers, it is desired to eliminate the traditional isolators, which correspondingly increases the likelihood of excessive differential motion between the access heads and the disk during Z-shock. To recover this loss of shock resistance, the spacing between the disks may be increased, yet this, however, correspondingly decreases the volumetric density of the disk drive and its ability to store a large volume of data.
Accordingly, it is desired to provide a disk drive having improved shock resistance without the need for conventional external isolators and without diminishing the maximum data storage capability of the disk drive in specific form factor, such as 3.5 inches for example.